This invention relates to a disc cartridge, and more particularly to a disc cartridge which permits a recordable/reproducible disc shaped medium such as an optical disc, a magneto-optical disc or the like removably received therein.
A disc shaped medium such as an optical disc, a magneto-optical disc or the like is generally classified into three types. One type or a first type is a disc shaped medium mounted in a recording/reproducing apparatus while being uncovered. Another type or a second type is a disc shaped medium mounted in a recording/reproducing apparatus while being unremovably received in a casing. The other or a third type is a disc shaped medium removably received in a casing. The third type disc shaped medium is mounted in a recording/reproducing apparatus while being either received in the casing or removed from the casing, resulting in being uncovered.
The first type disc shaped medium is represented by, for example, a compact disc (CD) and the second type disc shaped medium is represented by, for example, a mini-disc (MD).
The third type disc shaped media include, for example, a CD-ROM received in a CD caddie and the like. Removable arrangement of a CD-ROM in a CD caddie permits the CD-ROM to accommodate to both a reproducing apparatus of the type that the CD-ROM is mounted therein while being removed from the CD caddie and a reproducing apparatus of the type that the CD-ROM is mounted therein while being received in the CD caddie.
Also, there has been recently known a DVD which is an optical disc medium of the mass storage type. The DVDs proposed include a DVD-ROM, as well as a DVD-RAM. Further, it is proposed to construct a DVD-RAM so that it is not only operated in a recording/reproducing apparatus while being received in a cartridge, but removed from a cartridge so as to accommodate to a reproducing apparatus for a DVD-ROM in which a DVD is mounted therein while being uncovered.
A variety of structures are proposed for a disc cartridge for a DVD-RAM or the like. For example, there is known a structure which is so constructed that a cover is detachably or rotatably arranged on a side of cartridge opposite to a side of the cartridge on which a shutter is disposed, resulting in the cover being opened and closed for removal of a disc shaped medium from a casing. Such a structure is disclosed in Japanese Patent Application Laid-Open Publication No. 87677/1988 or the like.
Also, a structure for removing a disc shaped medium from a disc cartridge is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 266669/1988, which is so constructed that a cover is pivotally mounted on an upper surface section of a disc cartridge. However, the structure fails to permit a shutter for exposing the disc shaped medium during recording and reproducing operation to be arranged on the cover. Thus, the structure fails to be applied to a disc cartridge of the type that an opening for inserting a recording/reproducing head and a drive shaft therethrough into the disc cartridge are provided on each of both upper and lower sides of the disc cartridge.
When the conventional disc cartridge described above in which the DVD-RAM or the like is received is constructed to have a cover-detachable structure, there possibly occurs loss of the cover when the cover is separated from a casing of the disc cartridge for removal or takeout of the disc shaped medium from the cartridge.
Whereas, when the disc cartridge is constructed so as to rotatably mount the cover on the casing of the disc cartridge, it is required to form a pivot shaft of the cover and a bearing therefor to have a small size, to thereby form an opening to have a size greater than an outer diameter of the disc shaped medium such as the DVD-RAM or the like. Unfortunately, this causes the disc cartridge to be readily broken due to application of shock thereto or the like, to thereby be deteriorated in endurance and reliability.
Also, when the disc cartridge is applied to a recordable/reproducible disc shaped medium such as a DVD-RAM or the like, it is required to provide the disc cartridge with an erasure preventing mechanism.
When it is desired to provide the above-described rotation-type cover with such an erasure preventing mechanism, it is required that an operation projection of an erasure preventing member and a detection projection thereof be arranged so as not to interfere with a casing of the disc cartridge. Also, in this instance, the rotation-type cover is required to be operated by a slide mechanism moved so as to describe a locus of circular motion. Such arrangement of the rotation-type cover causes movement of the cover to be highly complicated, resulting in operability of the cover being deteriorated. Further, It causes the erasure preventing mechanism to be subject to structural restriction, resulting in being deteriorated in operability.
The present invention has been made in view of the foregoing disadvantages.
Accordingly, it is an object of the present invention to provide a disc cartridge which is capable of enhancing durability, reliability and operability of a cover while ensuring smooth removal of a disc shaped medium from the disc cartridge.
It is another object of the present invention to provide a disc cartridge which is capable of enhancing operability of an erasure preventing mechanism.
In accordance with the present invention, a disc cartridge is provided. The disc cartridge includes a casing constituted of an upper casing member and a lower casing member joined to each other and a cover arranged between the upper casing member and the lower casing member in a manner to be drawable out of the casing and rotatably mounted thereon with a recordable/reproducible disc shaped medium. The upper casing member and lower casing member are each formed with an opening through which a recording/reproducing head and a drive shaft of a recording/reproducing apparatus are inserted into the casing. The disc cartridge also includes a shutter formed to have a U-shape in section and slidably arranged on the casing so as to selectively open and close the openings of the upper casing member and lower casing member. The disc cartridge further includes an erasure preventing plug arranged in the cover. The upper casing member and lower casing member are formed with first and second cutouts, respectively, and the cover is provided with first and second projections fitted in the first and second cutouts of the upper casing member and lower casing member, respectively. The first and second cutouts of the upper casing member and lower casing member and the first and second projections of the cover cooperate with each other to provide an operation hole for the erasure preventing plug and a detection hole therefor, respectively.
In a preferred embodiment of the present invention, the erasure preventing plug includes an operation projection fitted in the operation hole and a detection projection fitted in the detection hole.
In a preferred embodiment of the present invention, the cover includes a front wall arranged on a side of the casing opposite to a side of the casing on which the shutter is arranged and is formed with a recess for receiving the erasure preventing plug. The recess of the cover is provided on an inner surface of the front wall with the first projection in a manner to be adjacent to one end of the erasure preventing plug when the erasure preventing plug is located at a recordable position which permits recording of information on the disc shaped medium.
In a preferred embodiment of the present invention, the recess of the cover is provided with a hole formed in a bottom wall thereof so as to be open to the detection hole. The second projection of the cover is arranged on the bottom wall in a manner to downwardly protrude from a part of a rim of the hole and to be contiguous to the front wall of the cover.
In a preferred embodiment of the present invention, the operation projection of the erasure preventing plug and the first projection of the cover are so formed that upper end surfaces thereof are flush with an upper surface of the upper casing member.
In a preferred embodiment of the present invention, the detection projection and the second projection of the cover are so formed that lower end surfaces thereof are flush with a lower surface of the lower casing member.